1. Technical Field
The present disclosure relates to apparatuses and a methods for the application of topical negative pressure (TNP) therapy to wounds. In particular, but not exclusively, the present disclosure relates to controlling pressure provided by a TNP device and alerting users to malfunctions.
2. Description of the Related Art
There is much prior art available relating to the provision of apparatus and methods of use thereof for the application of TNP therapy to wounds together with other therapeutic processes intended to enhance the effects of the TNP therapy. Examples of such prior art include those listed and briefly described below.
TNP therapy assists in the closure and healing of wounds by reducing tissue oedema; encouraging blood flow and granulation of tissue; removing excess exudates and may reduce bacterial load and thus, infection to the wound. Furthermore, TNP therapy permits less outside disturbance of the wound and promotes more rapid healing.
In our co-pending International patent application, WO 2004/037334, apparatus, a wound dressing and a method for aspirating, irrigating and cleansing wounds are described. In very general terms, this application describes the treatment of a wound by the application of topical negative pressure (TNP) therapy for aspirating the wound together with the further provision of additional fluid for irrigating and/or cleansing the wound, which fluid, comprising both wound exudates and irrigation fluid, is then drawn off by the aspiration means and circulated through means for separating the beneficial materials therein from deleterious materials. The materials which are beneficial to wound healing are recirculated through the wound dressing and those materials deleterious to wound healing are discarded to a waste collection bag or vessel.
In our co-pending International patent application, WO 2005/04670, apparatus, a wound dressing and a method for cleansing a wound using aspiration, irrigation and cleansing wounds are described. Again, in very general terms, this document utilizes similar apparatus to that in WO 2004/037334 with regard to the aspiration, irrigation and cleansing of the wound, however, it further includes the important additional step of providing heating means to control the temperature of that beneficial material being returned to the wound site/dressing so that it is at an optimum temperature, for example, to have the most efficacious therapeutic effect on the wound.
In our co-pending International patent application, WO 2005/105180, apparatus and a method for the aspiration, irrigation and/or cleansing of wounds are described. Again, in very general terms, this document describes similar apparatus to the two previously mentioned documents hereinabove but with the additional step of providing means for the supply and application of physiologically active agents to the wound site/dressing to promote wound healing.
The content of the above references is included herein by reference.
However, the above apparatus and methods are generally only applicable to a patient when hospitalized as the apparatus is complex, needing people having specialist knowledge in how to operate and maintain the apparatus, and also relatively heavy and bulky, not being adapted for easy mobility outside of a hospital environment by a patient, for example.
Some patients having relatively less severe wounds which do not require continuous hospitalization, for example, but whom nevertheless would benefit from the prolonged application of TNP therapy, could be treated at home or at work subject to the availability of an easily portable and maintainable TNP therapy apparatus.
GB-A-2 307 180 describes a portable TNP therapy unit which may be carried by a patient clipped to belt or harness. It will be appreciated however that there may be certain inaccuracies associated with the provision of a desired pressure or flow rate at a wound site.
Pressure and flow rate provided by the pump must fall within predetermined desired threshold values. It will be appreciated that with prior known pump units a problem is that as the pump wears over time or when certain environmental factors change, the pressure and flow rate provided by the pump can vary which can cause complications or non-ideal environments.
Also with prior known TNP units the control of pressure particularly on ‘start-up’ of the TNP system or when a new desired pressure is entered by a user can lead to undesirable effects. For example under certain circumstances prior known control mechanisms drive a pump too hard which can damage pump components and thus lead to the need for costly replacement. Also during use a rapid increase or decrease in pump speed can often lead to audible effects. This can concern a user who may think that the TNP system is faulty. Still further rapid changes can lead to pressure ‘over shooting’ a target value which can lead to increased pain and on occasions bleeding. A rapid change in pressure resulting in pain and discomfort to a patient may lead to immediate fear and rejection by the patient. Also in certain known techniques a user has little or no ability to control pressure provided by a pump.
Another problem which can occur is that when a canister utilized to filter and store waste product becomes full correct operation of the TNP system can be impeded.
In common with most prior art TNP therapy apparatus, the apparatus described cannot differentiate between a blocked or kinked aspiration conduit leading from a dressing to a waste canister and a blockage of the canister itself due to it being full, for example. The alarm to the user on this apparatus can be caused by a number of different faults or conditions.
Also, with current devices two pressure sensors are required on each side of a canister to detect such an event. A change in measured pressure between the two sensors implies a blocked canister filter which further implies a full canister. It will be appreciated that the use of two such sensors is both expensive and prone to error and requires complex processing elements to determine when a canister is full.
It is an aim of some embodiments to at least partly mitigate the above mentioned problems.
It is an aim of some embodiments to provide a method and apparatus of determining a negative pressure and flow rate generated by a pump of a topical negative pressure (TNP) system.
It is an aim of some embodiments to provide control of a suction pump of a topical negative pressure system without requiring both a pressure sensor and flow meter in the system.
It is an aim of some embodiments to provide a method and apparatus for controlling pressure provided by a pump of a topical negative pressure (TNP) system. Another aim is to determine the pressure provided in a controlled manner without over or under exerting a pump or without causing rapid noise changes during use.
It is an aim of some embodiments to provide a method and apparatus for controlling pressure so that jitter and noise caused by sudden changes in pump speed are reduced or avoided altogether.
It is an aim of some embodiments to provide a method and apparatus which allows for early detection of leaks in a TNP system.
It is an aim of some embodiments to provide a method and apparatus of determining status of a canister of a TNP system. More particularly, but not exclusively, it is an aim of some embodiments to provide a method and apparatus for determining when a canister of a TNP system is full.
It is an aim of some embodiments to provide an indication of when a canister of a TNP system is full without a requirement for two pressure sensors in the TNP system.
It is an aim of some embodiments to provide an apparatus which is able to distinguish between at least some distinct aspirant fluid non-flow conditions in TNP therapy apparatus so that a user is appropriately informed.
For purposes of summarizing the disclosure, certain aspects, advantages and novel features have been described herein. It is to be understood that not necessarily all such advantages can be achieved in accordance with any particular embodiment disclosed herein. Thus, the disclosure described herein can be embodied or carried out in a manner that achieves or optimizes one advantage or a group of advantages as taught herein without necessarily achieving other advantages as can be taught or suggested herein.